Ice breaking passive bow

ABSTRACT

An ice breaking ship comprising a metallic ice breaking bow structure independent from the true ship bow structure, the ice breaking bow structure being connected to the ship bow in such a manner as to be free to slide and to rotate into a vertical plane within a certain angle with respect to the ship bow, means being provided for rigidly securing the said ice breaking bow to the ship bow structure during the inefficiency periods of the said ice breaking bow.

United States Patent Iozza [54] ICE BREAKING PASSIVE BOW [72] lnventor: Emanuele Iozza, 30, Via Orsini,

Genoa, Italy [22] Filed: Jan. 11, 1971 [21] Appl. No.: 105,378

[30] Foreign Application Priority Data March 18,1970 ltaly ..12554/70 April 2, i970 ltaly 12592/70 [52] U.S. Cl ..l14/41 [51] Int. Cl. ..B63b 35/08 [58] Field of Search ..l 14/40-42 [56] References Cited UNITED STATES PATENTS 3,545,395 l2/l970 Rastorguev etal; ..ll4/4l 1 Dec. 19, 1972 Waas et al 14/41) Langballe ..l 14/40 Primary ExaminerTrygve M. Blix Attorney-Murray Schaffer [57] ABSTRACT An ice breaking ship comprising a metallic ice breaking how structure independent from the true ship bow structure, the ice breaking bow structure being connected to the ship bow in such a manner as to be free to slide and to rotate into a vertical plane within a certain angle with respect to the ship bow, means being provided for rigidly securing the said ice breaking bow to the ship bow structure during the inefficiency periods of the said ice breaking bow.

6 Claims, 14 Drawing Figures PATENTED DEC 19 m2 SHEET 1 [1F 5 PATENTED M1: 19 1912 SHEET 3 OF 5 r1 N om N? PATENTEDMBIQ m2 3,706,295

ET s UF 5 E510 qgxtg 40 v I P145 ATTORNEY PATENTED DEC 19 I972 SHEET 5 [IF 5 ICE BREAKING PASSIVE BOW BACKGROUND OF THE INVENTION propulsion plant is consumed in the elastic deformation of the ship, while only a partial amount is available for the ice breaking operation. i

3. As a consequence of the above, the ship structure needs to be properly reinforced, and the power plant needs to be properly overdimensioned, thus increasing the production and the operation costs of the ship.

The present invention aims to obviate to the above and other disadvantages of the known ice breakers.

SUMMARY OFTHEIYNYENTION According to the invention, the ship bow is provided with a bulbous bow extension, and is sidewise provided with transverse sliding guides, into which the side portions of the ice breaking bow are guided for a sliding and rotational movement into a vertical plane. To this end, the ice breaking bow extension is formed with a substantially U shaped stern portion, embracing the ship bow, and with an elongated bow portion, which is designed to act as an ice breaking ram. Means are provided for rigidly securing the ice breaking bow to the true ship bow during navigation.

According to a further development of the invention, the bulbous portion-of the ship bow extends beneath the movable ice breaking bow, and cooperates therewith to exert a shearing action on the ice-floe compressed therebetween, so as to increase the ice breaking efficiency of the ice breaking bow.

Elastic cushion means are interposed between the true bow and the movable ice breaking bow.

Further characteristic features of the invention will become more evident from the following specification made with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic longitudinal section through the bow of an ice breaker equipped with an ice breaking passive bow according to one embodiment of the invention, in the navigation trim.

FIG. 2 is a top plan view of the ice breaking bow according to FIG. 1.

FIGS. 3 to 6 show the different steps of bringing the ice breaking passive bow into operational trim.

FIG. 7 is' a section corresponding to the section of FIG. 1, of a second embodiment of the invention.

FIG. 8 is a transversal section through line VIII-VIII of FIG. 7.

FIG. 9 is a top plan view of the ice breaking bow of FIG. 7.

FIGS. 10 to 13 show the different steps for bringing the ice breaking passive bow of the embodiment of FIG. 7 into operational trim, and

FIG. 14 is a front view of the ice breaking bow of FIG.'7, during the final ice breaking step.

DESCRIPTION OF THE FIRST EMBODIMENT OF THE INVENTION With reference to the FIGS. 1 and 2 of the drawings, 1 generally denotes the true or proper bow of the hull of ice breaker ship. I

The bow 1 is provided with a bulbous extension 2, lying below the water line of the ship, which is connected to the deck plane of the ship by means of inwardly slanting sides 3.

The ice breaking bow extension4 is connected to the bow l of the ship. The ice breaking extension comprises a bow section 41 shaped so as to provide the best ice breaking action extending like a ram from the true bow .of the ship 1, and an U shaped stern section 42 shaped so *as to mate, with its internal sides and with a suitable clearance, with the bow section 1. The said U shaped stern section is provided with a pair of sidewise beams. 142, substantially extending flush with the sides 5 of the ice breaker ship. The beams 14 are each provided at their ends with an inwardly extending thrust shoe 242 slidably. housed within a corresponding groove 342 formed in the ships sides. The grooves 342 slope downwardly, and the shoes 242 are provided with curbed thrust surfaces. The upper end of each of the shoes 242 is providedwith a head piece 442 of a cross section equal to the cross section of the grooves 342 so as to make fast the shoes inside of grooves 342 when the ice breaking bow is in its non operational trim.

Elastic cushioning means, in the form of elastic .fenders 6 are provided between the true bow 2 and the ice breaking bow 4. The ice breaking bow is provided on its inner sides with recesses 107 into which are slidably mounted the sliding blocks 7 which are driven, for a to and fro movement toward corresponding recesses formed into the bow 1 of the ship by means of suitable hydraulic cylinders (not shown).

The operation of the just described ice breaking bow in passive condition will be now described with further reference to FIGS. 3 to 6.

In FIG. 1 the ice breaking bow is shown in its normal passive navigation trim. As shown, the passive bow 4 is ballasted so as 'to have its center of gravity in the zone of the elastic fenders 6, so as to bear on said fender and on the ship bow in a self balanced manner. This ballasting of the bow is performed in a known manner by means of suitable liquids (oil or water) pumped into suitable compartments formed into the bow. With the bow in the position shown in FIG. 1, the sliding blocks 7 are caused to slide into the recesses formed into the bow 2, so as to firmly connect the ice breaking passive bow to the ship true bow.

To bring the passive bow into ice breaking trim, the following operations are performed:

The sliding blocks 7 are retracted into their housings 107, so as to free the ice breaking bow from the ship bow. The ice breaking bow is thereafter deballasted, by pumping the ballast liquid from its inside into, for instance, suitable compartments of the ice breaking ship. In this manner, the ice breaking bow 4 is caused to slide upwardly with respect to the ship bow, as shown in FIG. 3, due also to the elastic expansion of the rubber fenders 6. During this movement, the shoes 242 slide along their guides 342. The deballasting of the ice breaking bow is performed so as to shift its center of gravity toward the bow, so that'the said ice breaking bow will assume a normally downward bow trim, as shown in FIG. 4, with the shoes sliding and rotating with respect to the guides 342, due to the arcuate conformation of their thrust surfaces so that the ice breaking bow pivots with respect to the true bow.

The icebreaking passive bow is now in the ice breaking trim.

Coming into contact with the pack 8, the ice breaking bow 4 rests a certain amount of its weight on it (FIG. 5). The more the ship pushes the passive bow 4 against the pack 8, the more the pack will lift the passive bow over the true bow (FIG. 6) of the ship, decreasing its buoyancy and consequently becoming more and more weighted down by it until it finally comes to the breaking point.

It will be appreciated that, in this manner, the ship structure is not elastically strained, and that by consequence the efficiency of the power plant of the ship for the ice breaking operation will be increased.

DESCRIPTION OF A SECOND EMBODIMENT OF THE INVENTION With reference to FIGS. 7 to 9, a second embodiment of the invention is shown, according to which the ice breaking passive bow cooperates with the ship true bow in the assault to the pack, so as to further improve the efficiency of the ice breaking action.

According to this embodiment, the true bow of the ship 10 is provided with a ram shaped bulbous extension 20,'lying beneath the water line of the ship. As described with reference to the previous embodiment of the invention, an ice breaking passive bow is slidably and rotatably connected to the ship true bow by means of the sliding guides 342 formed in the ship bow and the cooperating shoes 242 slidingly housed into said guides, and formed integral with the lateral beams 142 of the passive bow 40. The beams 142 extend the whole length of the passive bow, on both sides of the extension 20, and are connected together by the member 642, which straddles the bow extension of the true bow.

Means are provided for securing the passive bow to the true bow in the navigation trim, and elastical means are inserted between the true bow and the passive bow, as described for the previous embodiment.

In operation, (FIGS. 10 to 14) the passive bow is first disengaged from the true bow, by disengaging the coupling means 7.

Thereafter, the trim of the passive bow is caused to be varied, as described with reference to the FIG. 1 embodiment. During the ice breaking operation, the more the passive bow is lifted over the pack, the more its weight will be supported by the pack, the more the fore draft of the ship decreases. This will allow the ship to assault the pack on both its faces. The passive bow will pack. The pack will be stressed transversally (FIG. 14)

by forces of equal intensities and contrary signs which 'clutch it asit where into a huge press prepared for its bending and breaking.

It will be appreciated that according to this embodiment, a furthfr increase in efficiency is obtained.

From the oregomg, itls apparent that a very efficient ice breaking bow have been devised, providing for an efficient ice breaking action, without .unduly stressing the ship structure.

It is however to be understood that the invention shall not be limited tothe hereinbefore described embodiments of same, but shall include all constructions which may be deemed as based on the basic idea of the invention, as fully set above and as claimed hereinafter.

Iclaim:

l. A bowstructure for an ice breaking ship having a hull, a stem at one end and a bow at the other, said ice breaking bow structure comprising a substantially U- shaped body embracing the bow of said hull, said body having a forward ram portion extending therefrom and a pair of lateral beams extending rearwardly along the sides of said hull, each'of said beams having a shoe member, a guide member located on each side of said hull slidably receiving said corresponding shoe member permitting said body to move in a substantially vertical plane, said shoe members and said guide members having cooperating rounded thrust surfaces to permit said body to effect a rocking movement in addition to the vertical movement, elastic cushioning means located between said body and said hull and disengageable coupling means for selectively securing said body to said hull.

2. An ice breaking ship according to claim I, in which the said guide members are inclined with respect to the ships deck by an angle lesser than 3. An ice breaking ship according to claim 1, including means for ballasting and deballasting said ice break ing bow body, so as to change its trim by varying its center of gravity.

4. An ice breaking ship according to claim 1, in which the bow of said hull is provided with a ram like extension extending beneath the said movable ice breaking bow, and cooperating with the said ice breaking bow in the ice breaking operation.

5. An ice breaking ship according to claim 4, in which the said ice breaking bow straddles the said ram like ship bow extension.

6. An ice breaking .ship according to claim 4, in which the said ice breaking bow comprises a pair of lateral beams connected together by an intermediate upper structure, the said ram like ship bow extension extending between said beams below the said upper structure. 

1. A bow structure for an ice breaking ship having a hull, a stern at one end and a bow at the other, said ice breaking bow structure comprising a substantially U-shaped body embracing the bow of said hull, said body having a forward ram portion extending therefrom and a pair of lateral beams extending rearwardly along the sides of said hull, each of said beams having a shoe member, a guide member located on each side of said hull slidably receiving said corresponding shoe member permitting said body to move in a substantially vertical plane, said shoe members and said guide members having cooperating rounded thrust surfaces to permit said body to effect a rocking movement in addition to the vertical movement, elastic cushioning means located between said body and said hull and disengageable coupling means for selectively securing said body to said hull.
 2. An ice breaking ship according to claim 1, in which the said guide members are inclined with respect to the ship''s deck by an angle lesser than 90*.
 3. An ice breaking Ship according to claim 1, including means for ballasting and deballasting said ice breaking bow body, so as to change its trim by varying its center of gravity.
 4. An ice breaking ship according to claim 1, in which the bow of said hull is provided with a ram like extension extending beneath the said movable ice breaking bow, and cooperating with the said ice breaking bow in the ice breaking operation.
 5. An ice breaking ship according to claim 4, in which the said ice breaking bow straddles the said ram like ship bow extension.
 6. An ice breaking ship according to claim 4, in which the said ice breaking bow comprises a pair of lateral beams connected together by an intermediate upper structure, the said ram like ship bow extension extending between said beams below the said upper structure. 